Field of the Inventions
The present invention generally relates to protection of expandable tubular threads. More particularly, the present invention describes an expandable tubular with at least one centralizer as an integral part of the tubular, said centralizer protecting the expandable tubular threads. Furthermore, this invention relates to a downhole tubular or downhole assembly, e.g., for use in an oil/gas well or a water well.
Background of the Invention
In recent years, the use of expandable tubulars has become more common in the drilling and completion phases of well bore construction. In these phases, it is necessary to protect tubulars and related devices from scarring. For example, it is necessary to protect threaded connectors from scarring, when they are being placed in a well. It is also necessary to protect box threads during handling and storage.
Very often, the wall of the threaded box thread is very thin. This is caused by the minimum wall thickness to apply the thread. This thread outside diameter (OD) is easy to ding, scar or bend out of shape. If the box OD is scarred, the material will split while being expanded and cause a failure. The scars can be caused by the pipe rubbing the casing, casing connections, and other attachments while it is let down hole. The scarring also occurs with a directional change. An opening is often put in the casing to put the tubular through. These openings are rough and may have sharp and jagged edges, which will scar the tubular. In such cases, the tubular can split with excessive scarring, which results in a very expensive repair and lost time.
A current method to prevent such damages is to attach a steel protection sleeve by applying adhesive on the box OD with an epoxy glue applicator, as illustrated in FIG. 1, which represents the current method of attaching steel sleeves to protect connectors. Another method may be to use a brush or paddle stick. The sleeve is then slid over the box thread. When putting on the sleeve, the glue at times is pushed off by the sleeve. When the glue sets, there is no guarantee that the glue is in contact with the sleeve and box OD. There is also no guarantee that the glue is not thicker on one side or the other since there is no control to make sure that the glue covers the entire contact area evenly. In FIG. 1, 101 represents the protecting steel sleeve; 102 represents adhesive (or glue); 103 represents the tubular; 104 represents a connector; and 105 represents the box of the connector 104.
With the sleeve is installed in this manner, several undesirable situations can occur. (1) The sleeve touches the casing caused by the pressure of the tubing and seal. (2) The sleeve touches the casing while stacking the tubing or casing. (3) The sleeve hits the casing connectors. When any of the above three situations occurs, happens, the protective sleeve can break loose. If this happens, then the sleeve may run up the casing or tubing. Sometimes, several of these sleeves may become loose and come together, which will cause problem during tubular expansion. More seriously, there is no more protection for the threads. The threads can scar and split days later when expanded, causing extensive damage, incurring repair cost and lost time.
Accordingly, there is continuing need and interest to develop methods and systems to protect expandable tubular threads.